Source code for django.template.engine

import warnings

from django.core.exceptions import ImproperlyConfigured
from django.utils import lru_cache, six
from django.utils.deprecation import RemovedInDjango110Warning
from django.utils.functional import cached_property
from django.utils.module_loading import import_string

from .base import Context, Template
from .context import _builtin_context_processors
from .exceptions import TemplateDoesNotExist
from .library import import_library

_context_instance_undefined = object()
_dictionary_undefined = object()
_dirs_undefined = object()


[docs]class Engine(object): default_builtins = [ 'django.template.defaulttags', 'django.template.defaultfilters', 'django.template.loader_tags', ] def __init__(self, dirs=None, app_dirs=False, allowed_include_roots=None, context_processors=None, debug=False, loaders=None, string_if_invalid='', file_charset='utf-8', libraries=None, builtins=None): if dirs is None: dirs = [] if allowed_include_roots is None: allowed_include_roots = [] if context_processors is None: context_processors = [] if loaders is None: loaders = ['django.template.loaders.filesystem.Loader'] if app_dirs: loaders += ['django.template.loaders.app_directories.Loader'] else: if app_dirs: raise ImproperlyConfigured( "app_dirs must not be set when loaders is defined.") if libraries is None: libraries = {} if builtins is None: builtins = [] if isinstance(allowed_include_roots, six.string_types): raise ImproperlyConfigured( "allowed_include_roots must be a tuple, not a string.") self.dirs = dirs self.app_dirs = app_dirs self.allowed_include_roots = allowed_include_roots self.context_processors = context_processors self.debug = debug self.loaders = loaders self.string_if_invalid = string_if_invalid self.file_charset = file_charset self.libraries = libraries self.template_libraries = self.get_template_libraries(libraries) self.builtins = self.default_builtins + builtins self.template_builtins = self.get_template_builtins(self.builtins) @staticmethod @lru_cache.lru_cache()
[docs] def get_default(): """ When only one DjangoTemplates backend is configured, returns it. Raises ImproperlyConfigured otherwise. This is required for preserving historical APIs that rely on a globally available, implicitly configured engine such as: >>> from django.template import Context, Template >>> template = Template("Hello {{ name }}!") >>> context = Context({'name': "world"}) >>> template.render(context) 'Hello world!' """ # Since Engine is imported in django.template and since # DjangoTemplates is a wrapper around this Engine class, # local imports are required to avoid import loops. from django.template import engines from django.template.backends.django import DjangoTemplates django_engines = [engine for engine in engines.all() if isinstance(engine, DjangoTemplates)] if len(django_engines) == 1: # Unwrap the Engine instance inside DjangoTemplates return django_engines[0].engine elif len(django_engines) == 0: raise ImproperlyConfigured( "No DjangoTemplates backend is configured.") else: raise ImproperlyConfigured( "Several DjangoTemplates backends are configured. " "You must select one explicitly.")
@cached_property def template_context_processors(self): context_processors = _builtin_context_processors context_processors += tuple(self.context_processors) return tuple(import_string(path) for path in context_processors) def get_template_builtins(self, builtins): return [import_library(x) for x in builtins] def get_template_libraries(self, libraries): loaded = {} for name, path in libraries.items(): loaded[name] = import_library(path) return loaded @cached_property def template_loaders(self): return self.get_template_loaders(self.loaders) def get_template_loaders(self, template_loaders): loaders = [] for template_loader in template_loaders: loader = self.find_template_loader(template_loader) if loader is not None: loaders.append(loader) return loaders def find_template_loader(self, loader): if isinstance(loader, (tuple, list)): args = list(loader[1:]) loader = loader[0] else: args = [] if isinstance(loader, six.string_types): loader_class = import_string(loader) if getattr(loader_class, '_accepts_engine_in_init', False): args.insert(0, self) else: warnings.warn( "%s inherits from django.template.loader.BaseLoader " "instead of django.template.loaders.base.Loader. " % loader, RemovedInDjango110Warning, stacklevel=2) return loader_class(*args) else: raise ImproperlyConfigured( "Invalid value in template loaders configuration: %r" % loader) def find_template(self, name, dirs=None, skip=None): tried = [] for loader in self.template_loaders: if loader.supports_recursion: try: template = loader.get_template( name, template_dirs=dirs, skip=skip, ) return template, template.origin except TemplateDoesNotExist as e: tried.extend(e.tried) else: # RemovedInDjango20Warning: Use old api for non-recursive # loaders. try: return loader(name, dirs) except TemplateDoesNotExist: pass raise TemplateDoesNotExist(name, tried=tried)
[docs] def from_string(self, template_code): """ Returns a compiled Template object for the given template code, handling template inheritance recursively. """ return Template(template_code, engine=self)
[docs] def get_template(self, template_name, dirs=_dirs_undefined): """ Returns a compiled Template object for the given template name, handling template inheritance recursively. """ if dirs is _dirs_undefined: dirs = None else: warnings.warn( "The dirs argument of get_template is deprecated.", RemovedInDjango110Warning, stacklevel=2) template, origin = self.find_template(template_name, dirs) if not hasattr(template, 'render'): # template needs to be compiled template = Template(template, origin, template_name, engine=self) return template
# This method was originally a function defined in django.template.loader. # It was moved here in Django 1.8 when encapsulating the Django template # engine in this Engine class. It's still called by deprecated code but it # will be removed in Django 1.10. It's superseded by a new render_to_string # function in django.template.loader. def render_to_string(self, template_name, context=None, context_instance=_context_instance_undefined, dirs=_dirs_undefined, dictionary=_dictionary_undefined): if context_instance is _context_instance_undefined: context_instance = None else: warnings.warn( "The context_instance argument of render_to_string is " "deprecated.", RemovedInDjango110Warning, stacklevel=3) if dirs is _dirs_undefined: # Do not set dirs to None here to avoid triggering the deprecation # warning in select_template or get_template. pass else: warnings.warn( "The dirs argument of render_to_string is deprecated.", RemovedInDjango110Warning, stacklevel=3) if dictionary is _dictionary_undefined: dictionary = None else: warnings.warn( "The dictionary argument of render_to_string was renamed to " "context.", RemovedInDjango110Warning, stacklevel=3) context = dictionary if isinstance(template_name, (list, tuple)): t = self.select_template(template_name, dirs) else: t = self.get_template(template_name, dirs) if not context_instance: # Django < 1.8 accepted a Context in `context` even though that's # unintended. Preserve this ability but don't rewrap `context`. if isinstance(context, Context): return t.render(context) else: return t.render(Context(context)) if not context: return t.render(context_instance) # Add the context to the context stack, ensuring it gets removed again # to keep the context_instance in the same state it started in. with context_instance.push(context): return t.render(context_instance)
[docs] def select_template(self, template_name_list, dirs=_dirs_undefined): """ Given a list of template names, returns the first that can be loaded. """ if dirs is _dirs_undefined: # Do not set dirs to None here to avoid triggering the deprecation # warning in get_template. pass else: warnings.warn( "The dirs argument of select_template is deprecated.", RemovedInDjango110Warning, stacklevel=3) if not template_name_list: raise TemplateDoesNotExist("No template names provided") not_found = [] for template_name in template_name_list: try: return self.get_template(template_name, dirs) except TemplateDoesNotExist as exc: if exc.args[0] not in not_found: not_found.append(exc.args[0]) continue # If we get here, none of the templates could be loaded raise TemplateDoesNotExist(', '.join(not_found))
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